<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        /** {
            margin: 0;
            padding: 0;
        }*/
        div.b1 {
            display: inline-block;
            width: 200px;
            border: 1px solid red;
            margin: 20px;
            padding: 15px;
        }
        div.b2 {
            display: inline-block;
            box-sizing: border-box;
            width: 200px;
            border: 1px solid red;
            margin: 20px;
            padding: 15px;
        }
    </style>
</head>
<body>
<p>width/height默认为内容高宽</p>
<div class="b1">
    <ul>
        <li>List Item 1</li>
        <li>List Item 2</li>
        <li>List Item 3</li>
        <li>List Item 4</li>
        <li>List Item 5</li>
    </ul>
</div>
<hr>
<p>box-sizing: border-box. 使width/height值按边框内计算，但不包括margin值</p>
<div class="b2">
    <ul>
        <li>List Item 1</li>
        <li>List Item 2</li>
        <li>List Item 3</li>
        <li>List Item 4</li>
        <li>List Item 5</li>
    </ul>
</div>
</body>
</html>